(HER ●) @ Don Quijote (aka DONKI, a discount chain store where you can find anything) in Yokohama, I found half of the 2nd floor full of FAKE EYELASHES. Lovely!
I have been wearing fake eyelashes since 6th grade. I used to have trouble finding the best ones since there weren't many companies making them, but now I see very high competition! Through my 9-10 years of experience with fake lashes I have learnt that the key to beautiful looking fake eyelashes is the GLUE.
Japanese fake lashes have a thick base (where the fake hair starts) so it tends to take time for the lashes to get flexible so that it fits the shape of your eye (I think Japanese lashes have a thick base just for better quality. I used to be able to use a pair of Japanese lashes for 6 months). Thick bases are good for quality, but sometimes the lashes get too heavy, or the base starts hurting your eyelid. The lashes I've bought in the US tend to have a thinner base making it flexible and easier for use, but of course they don't last long as long.
Fake eyelashes are extremely popular now in Japan from various age groups (even 50+ year olds!) due to the great variety and types they sell. They are also easily accessible since even pharmacies and convenience stores sell them!
The cheapest fake eye lashes you can find is probably at Donki, where 1 pair is only 99 YEN (1USD). They also have packs of several lashes for a great price too!